Cat defecating outside litter box only during the night

We recently adopted a cat from a hoarder who had 20 cats in her home. He has diarrhea which we are treating with an antibiotic.

During the day he urinates and defecates (very watery) in his litter box, but each morning when we awake, he has defecated on the hardwood floor, never the carpeted areas.

He has two boxes and we keep them very clean. We are very frustrated with this behavior.

My thoughts:

Thank you for taking him in, Cynthia. I'm sorry to hear that he's having troubles.

My first thought is that he's been through a lot if he was living with a hoarder. I'm glad to hear that he's been to the vet and is being treated.

I'd like to think that as he adjusts and his diarrhea clears up that this problem will go away.

Since he only exhibits this behavior at night, I'm thinking it's either a vision problem, or a cleaning schedule problem.

Many cats that come from haording situations often have multiple physical and personality issues. They're often not fed a good diet and may suffer from malnutrition. Is it possible that he has some night vision problems?

Are these litter boxes in an area of the house that's perhaps too dark at night? If so, try setting up a night light near the boxes so that he can see better. If the boxes are covered or hooded, take the covers off as that keeps the light out. See what happens.

If he urinates in the box at night, that doesn't necessarily mean he's not having vision issues, it just means he's OK with urinating and not defecating. Or, his schedule is such that the defecation occurs when it's darker.

Speaking of schedules... you're keeping the boxes very clean which is great, but think about whether or not your cleaning schedule matches his box use. If you're not already, try cleaning the boxes twice a day, and make sure one of those times is right before you go to bed so that the boxes are at their cleanest at night.

I hope that gives you some ideas. Please let us know how he gets on, and thank you again for adopting him!-Kurt

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